This invention relates to radiant tube space heating appliances of the kind comprising branched or other radiation ducting, commonly suspended overhead in the space to be heated, an exhaust fan or other pump in a tailpipe of the ducting for drawing a flow of gases there through in use, and a series of inline fluid fuelled burner assemblies, typically gas fired and automatically controlled, upstream of the tailpipe for generating heat carried by said flow. Radiant heat is emitted from the ducting surfaces and this is commonly directed and concentrated, e.g. in a downward direction, by one or more reflectors mounted above or to the side of the ducting. Said appliances are hereinafter referred to as "continuous radiant tube heating appliances".
An example of one known construction of continuous radiant tube heating appliance is described in our GB 2,274,703-A and EP 0606782-A.
The object of the invention is to provide a continuous radiant tube heating appliance giving high performance with safety, reliability, and economy of operation.
According to the invention there is provided a continuous radiant tube heating appliance as hereinbefore defined including a control damper in the tailpipe selectively operable to throttle the flow of gases induced by the fan or other pump, a power actuator for adjusting the damper, and automatic control means including a temperature sensor responsive to the temperature of gases passing along the tailpipe in use and controlling operation of the actuator so as to reduce the induced flow when said temperature is below a predetermined level as on start-up of the appliance from cold.
Typically the appliance will comprise a single branch; or two or more ducting branches acting in parallel and with separate input ends through which individual flows of air are drawn during operation, each branch having a burner assembly or series of burner assemblies spaced along its length and all the branches being connected to a common tallpipe and exhaust fan associated with said control means.
A pre-set balancing damper may be included at the downstream end of each said branch upstream of the tailpipe.
Preferably the control damper and automatic control means are constructed as a unit to include a section of the tailpipe with the temperature sensor therein in close proximity to the damper providing simple installation by coupling into the other parts of the tailpipe and with an electrically powered actuator merely requiring connection to a power supply.